Based on what data does vk.com suggest possible friends?

Question

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Hello.
I recently noticed that VK offers my fake account friends whom I know in real life, but I could not communicate through this profile with them or mutual friends.
There is no information in the profile, except for the phone number, which, by the way, is shown only to those who are on the friends list.
I could assume that VK stores cookies and suggests friends based on them. But, I use the main VK profile ONLY on a computer, and I offer friends on all other devices through which I have never authorized before.
PS. Vkontakte support did not answer anything, saying only that none of my personal information was collected or disclosed. Oh well.